Data from: What's that smell? Hummingbirds avoid foraging on resources with defensive insect compounds

Unlike many other vertebrates, the presence and role of functional olfactory systems in birds are only recently attracting attention. For example, hummingbirds utilize visual cues to locate flowers, but little is known about the role olfaction plays in foraging despite observations that hummingbirds avoid resources occupied by certain insects. We investigated the behavioural responses of both wild and captive hummingbirds to olfactory cues of hymenopteran floral visitors, including native wood ants (Formica francoeuri), invasive Argentine ants (Linepithema humile) and European honeybees (Apis mellifera). Although not known for their sense of smell, hummingbirds in this study exhibited the ability to distinguish insect chemical cues in different ecological contexts. Both wild and captive hummingbirds avoided foraging on feeders with defensive chemicals of F. francoeuri and aggregation pheromones of L. humile. Interestingly, no response to honeybee cuticular hydrocarbons was observed. Understanding the contexts in which these cues are perceived and how olfaction can shape foraging behaviour of hummingbirds adds to our understanding of foraging ecology in general.